Short answer
CBM is the volume of a shipment in cubic metres, and at its simplest it is the length, width and height of the package in metres multiplied together. What decides the freight cost, though, is usually neither volume nor weight alone but the chargeable weight found by comparing the two: the carrier takes whichever comes out higher. Attachment shipments are a special case in that calculation because attachments are heavy for their size; with products such as breakers and shears it is almost always weight that decides, not volume.
How CBM is calculated
For a single package the calculation is simple: length (m) × width (m) × height (m). Where there are several packages, each volume is calculated separately and added. The dimensions are the outer dimensions of the PACKAGE, not of the product; pallet height and packing thickness are included.
In sea freight, the common practice on part loads (LCL) is to treat one cubic metre as equivalent to a given weight and charge whichever of volume and weight is greater. In air freight, volumetric weight is calculated with a different divisor. Because those ratios vary by carrier and even by route, ask your forwarder in writing which ratio applies when you request a quote.
For full container (FCL) shipments the calculation changes: the price is given per container rather than per cubic metre. At that point your question is no longer "how many cubic metres" but "which container does this load fit into and does it exceed the weight limit".
With attachments, weight decides rather than volume
- Products such as hydraulic breakers, shears and pulverisers are dense and heavy; the weight limit is reached before the container volume is filled.
- The real constraint when loading attachments is therefore not the internal volume of the container but the permitted cargo weight.
- The weight limit is not only the container's own; road transport limits in the destination country can be the binding one.
- Light items such as tools, spare parts and packing material are used to fill the volume that remains.
- Distributing the load evenly inside the container is not a preference but a requirement; weight gathered at one end creates risk both in transport and in unloading.
Give the package dimensions, not the product dimensions
The commonest mistake when requesting a quote is giving the catalogue dimensions of the product. Freight is calculated on the packed dimensions: pallet, crate, blocking and protective material included. The gap between packed and catalogue dimensions is the commonest reason for a gap between quotation and invoice.
Do and don’t
Do
- Give dimensions as packed: length, width, height and gross weight.
- Ask the forwarder in writing which volume-to-weight ratio applies.
- On a heavy attachment, check the weight limit first and the volume second.
- Distribute the load evenly inside the container and secure it.
- Ask about road weight limits in the destination country in advance.
Don't
- Do not have freight calculated on catalogue dimensions.
- Do not take internal container dimensions from memory; they vary by type and by container, so confirm with the forwarder.
- Do not gather the weight at one end of the container.
- Do not treat securing as secondary; a load that shifts in transit damages both the product and the container.
- Do not learn the weight limit at the last minute; a surprise on loading day is the most expensive kind.
What the forwarder needs from you for a quote
- 1
Packing list
How many boxes or pallets, with the packed dimensions and gross weight of each. Total CBM and total gross weight come out of that list.
- 2
Loading and destination points
The address where the goods are collected and the port or door where they are delivered. The delivery term (incoterm) sets which of those two points your responsibility runs to.
- 3
Product description and HS code
Needed for customs formalities and any special transport conditions. The HS code also determines the duty rate in the destination country.
- 4
Handling constraints
Can it be stacked, from which side does a forklift enter, where are the lifting points. On attachments the centre of gravity is usually not at the geometric centre, and that information helps at unloading.
- 5
Timing expectation
The ready date and the expected arrival date. The choice between sea, road and air is usually decided by this expectation rather than by price.